In a scroll-type compressor of the prior art, as illustrated in FIGS. 1 and 2, a pin is provided to secure and locate a coupling ring to an adjacent part such as the scroll assembly or the compressor housing. In a typical prior art compressor, the pin comprises a roll pin or a solid pin which is press fit into both the coupling ring and the adjacent part. A through hole is provided in the coupling ring having a smaller diameter than the roll pin to form an interference fit. The adjacent part (the scroll or housing) has a similar undersize hole to form an interference fit with the roll pin.
In one prior art application, the pin is approximately 4 mm in diameter having approximately a 0.2 mm nominal interference fit to the hole provided in each of the components. Because of manufacturing tolerances, this interference fit may vary from 0 mm to 0.4 mm under normal conditions. However, excessive variation may result in a noninterference fit. Further, with larger interference fits, a large force is required for assembly. Typically, the coupling ring is made from steel and the pin is press-fit into the coupling ring. The coupling ring, having the pins installed, is then aligned to the adjacent part (either the scroll or housing, which may be made of aluminum), and the pin is then press-fit into the adjacent part. In the situation where a minimal interference fit is provided, the pin may become loose while the compressor is operating. In such an instance, the compressor may be damaged.
U.S. Pat. No. 4,340,339 discloses a second technique to rotationally engage a coupling ring to an adjoining component. Projections are provided on the coupling ring and radial slots are provided in the adjoining member. This technique is difficult and expensive to produce.
It would be desirable to provide a coupling ring assembly which is inexpensive and less sensitive to variation and which provides a secure retention of the pin.